final work for public rest api

[syjer]

This issue will track the last items that need to be done for the public rest api integration.

• ControllerExceptionHandler return a structured json result ? will be considered in another release if necessary

[syjer]

Note:

for request context utils removal:
search for: @RequestParam(required = false, name = "lang") .

Wherever it's used, we should always do:

-> ticket locale (if present)
-> specified locale by the user if in event
-> reservation locale (if present)
-> a locale of the event as a ultimate fallback

This rule can be applied for:

• generateTicketPdf ok
• sendTicketByEmail ok
• updateTicketInfo ok

Others:

• (admin) confirmPayment -> as a fallback for ticket locale -> ok
• reserveTicket -> for creating a new reservation -> client side ok
• confirmOverview -> for payment specification -> client side ok
• validateToOverview -> for updating reservation locale and as a fallback for ticket locale -> client side ok
• reSendReservationConfirmationEmail -> use locale passed as parameter -> client side ok

Additionally, review all use of:

Locale.forLanguageTag
new Locale( -> convert where it makes sense to Locale.forLanguageTag

edit: add a check constraint for language to be set at reservation and ticket level if the email field is present. Note: add value if null in script! Will be done later.

Implement: LocaleUtil.forLanguageTag(String, Event)

[syjer]

can be considered done. If others issues will pop up, they will be handled in a separate issue.